Texasweed (Caperonia palustris) is a weed known to affect rice and soybean crops throughout the Gulf Coast region of the United States. This weed, unfortunately, has been found to be extremely difficult to control. Currently available chemical herbicides, for example, are only effective against very small texasweed. Once texasweed has grown past the seedling stage, it is almost impossible to control using conventional herbicides.
Increased emphasis has been placed on the development of what are known as mycoherbicides. These involve the use of natural pathogens to control weeds. A fungus known to infect a weed is selected and cultured. The pathogen is then applied to the weed and allowed to normally infect the plant and kill it. The pathogen selected is one which does not affect the crop infested with the weed to be controlled.
An example of the use of mycoherbicides is the use of the fungus Colletotrichum gloeosporioides to control northern jointvetch (Aeschynomene virginica) in Arkansas rice and soybean production. This fungus is a known pathogen of northern jointvetch but does not affect the rice or soybean crops. The fungus is applied to this weed in an aqueous suspension.
One disadvantage with mycoherbicides is that the pathogens are generally specific for one variety or strain of weeds. Until now, no such mycoherbicide has been found which is effective in controlling texasweed.